[m-dev.] Bootstrapping Mercury with custom CFLA

[Keri Harris]

On 30/09/2017 16:11, Julien Fischer wrote:
> 
> Hi Keri,
> 
> On Sat, 30 Sep 2017, Keri Harris wrote:
> 
>> Is there a recommended way to specify custom (GCC) compiler flags when 
>> bootstrapping Mercury? Both CFLAGS and EXTRA_CFLAGS seem like obvious 
>> choices, but passing in either of them leads to build errors:
>>
>> $ make CFLAGS="..."
>>
>> gmake[2]: Entering directory '/home/keri/mercury-srcdist-14.01.1/util'
>> ../scripts/mgnuc --no-mercury-stdlib-dir \
>>       --grade hlc.gc    -- -march=native -O2 -pipe 
>> -frecord-gcc-switches -o
>>   mkinit \
>>         mkinit.c mkinit_common.c
>> mkinit.c:40:29: fatal error: mercury_conf.h: No such file or directory
>> compilation terminated.
>> mkinit_common.c:19:29: fatal error: mercury_conf.h: No such file or 
>> directory
>> compilation terminated.
>>
>> $ make EXTRA_CFLAGS="..."
>>
>> gmake[2]: Entering directory '/home/keri/mercury-srcdist-14.01.1/robdd'
>> ../scripts/mgnuc --no-mercury-stdlib-dir --grade hlc.gc.pregen       
>> -- -DNDEBUG -DNEW -DCLEAR_CACHES -DCOMPUTED_TABLE -DEQUAL_TEST 
>> -DUSE_ITE_CONSTANT -DRESTRICT_SET    -march=native -O2 -pipe 
>> -frecord-gcc-switches    -c bryant.c -o bryant.o
>> bryant.c:107:25: fatal error: mercury_imp.h: No such file or directory
>> compilation terminated.
> 
> The problem there is that you are setting CFLAGS and EXTRA_CFLAGS for
> make *not* mmake.  As a consequence you have ended up overriding the
> CFLAGS that mmake constructs with your CFLAGS.  (One of the things
> passed via CFLAGS is the location of the runtime header files, hence the
> error above.)
> 
> To do what you want add the variable definitions to a file named
> Mmake.params at the top-level of the source tree; mmake will pick them
> up from there and handle them appropriately.
> 
> For example, if Mmake.params contains
> 
>     EXTRA_CFLAGS = -O0
> 
> then mmake will append -O0 to every invocation of GCC.  (Note that GNU
> make's '+=', ':=' will also apply with mmake.)
> 
> (For the stage2 and stage3 compilers the file should be named
> Mmake.stage.params rather than Mmake.params.)
> 
>> My preference would be for the EXTRA_XXX flags (EXTRA_CFLAGS, 
>> EXTRA_LDFLAGS etc) to always be reserved for the user. Patching 
>> robdd/Mmakefile to avoid using EXTRA_CFLAGS would then allow the build 
>> to succeed; see attached patch for one way to do this.
> 
> They are reserved for the user; in this case the user happens to be the
> Mercury compiler itself.


Thanks for clearing that up; that makes perfect sense.


Regards

Keri